Power-operated extensible skimming blade

ABSTRACT

A reciprocating bridge with scraper and skimmer blades operates in a tank requiring skimming to the uneven sidewalls of the tank. Each end of the scraper is provided with a pivoted blade which is retracted when the blade is elevated. The blade is extended by a spring when the blade is lowered and the spring holds the blade against the sidewall of the tank at all times but with no unrequired force.

lJnited States Patent Weiss et a1.

Jan. 18, 1972 POWER-OPERATED EXTENSIBLE SKIMMING BLADE Gordon E. Weiss,Butler; John B. Rank, Milwaukee; Gilbert W. Quast, Brookfield, all ofWis.

Assignee: Rex Chainbelt, Inc., Milwaukee, Wis.

Filed: Oct. 16, 1970 Appl.N0.: 81,273

inventors:

[1.8. CI ..2l0/527 int. Cl ..B0ld 21/04 Field of Search ..2l0/525, 527

[56] References Cited UNITED STATES PATENTS 1,911,008 5/1933 Withington..2l0/527 X Primary Examiner.lim L. DeCesare Attorney-Ernst W. Schultzand Joseph J. .lochman, Jr.

[57] ABSTRACT A reciprocating bridge with scraper and skimmer bladesoperates in a tank requiring skimming to the uneven sidewalls of thetank. Each end of the scraper is provided with a pivoted blade which isretracted when the blade is elevated. The blade is extended by a springwhen the blade is lowered and the spring holds the blade against thesidewall of the tank at all times but with no unrequired force.

4 Claims, 3 Drawing Figures 1 rowan-creamer) sxrsssmrn SKIMMING sumsBACKGROUND or THE INVENTION Skimmer blades which are carried byflandbetween chains have been fitted at their'ends with-wipers vwhich'rub theskimming blade to' scrape the sidewalls of the tank. Each assemblyis-identical except that theya're rightand left handed and the samereference numbers are applied to the same parts.

sidewalls of the separation'tank. Such wipers wear outrapidly 7 andrequire regular maintenance..They require only some retraction becausethey move with the chains in the same relative direction at all times. Areciprocating bridge carrying a single skimming blade is most often usedwithlarge rectanguwhich are only roughly, or approximately, straight.

Such a bridge lifts the skimming blade at the end of the skimming runand for the return run may have toclear some projections such as somestructural parts of the tank.

SUMMARY OF THE INVENTION Theextension at each end of a skimming bla'deispivoted on a vertical axis aheadof the extremity of the .blade. Apart ofresilient means to hold them outwardly and do not require lar tanks ofconcrete construction very often having: sidewalls the blade adjoins acylindrical part of theextension to form a seal. A spring andcable are.connected to the extension and the carriage so that the raising andloweringof the'skimmer blade respectively retracts and extendsthe'scraper. blades.

. BRIEF DESCRIPTION OF THE-DRAWING FIG. 1 shows in side elevation andpartially in section, a

travelling bridges and the lowersn'ucture whichcarries a 3 scraper bladein the it raised position. The end view .of the skimming blade in thelower position is shown and a section of "The upper and lower bracketsdl'a'nd 42 are secured to the upper and lower edges of the blade 31 andextend forwardly thereof tocarry the vertical shaft 43. Scraper blade 40extends from the member 44 mounted on shaft 43 between brackets 41."Member 44 and the blade 40 together fonn acylindrical surface whichmaintains a nominal clearance with the block 45 fixed to the end ofblade 31. This clearance amounts to seal in that the oil being pushed bythe skimmer blade cannot pass therethrough because of its'relativelyhigh viscosity.

The operating levers fixed to the upper end of shaft 43 include theforward spring lever 46 which is connected by the "spring 47 to theblade 31. A series of holes in lever 46 allows for the selectiveadjustment of the spring.

n The other operating lever 49 fixed to the upper end of shah 43 extendsover skimming blade 31 and is operated by the cable 51. Cable 51operates over the pulley 52 carried by blade 31 and has its endsconnected to lever 49 and to brace 36 at a location below shaft 34 andbearing 35.

' The arrangement of the cable is'such that when skimming blade 31 is inits upper. position, the cable is in tension and its length is such thatspring 47 is expanded and the member 44 is f rotated away fromtheadjacent'iwallfand a substantial ously referred to, skimming blade 31is lowered and the effecthe blade is shown also in the upper position.This: additional upper position is taken approximately on Section 1-1 ofFIG.

I FIG. 2 is a plan-viewof the endof the skimming vbladeand includes partof the supporting structure.

tive length of cable 51 is increased so that spring 47 is operative toturn shaft 43 and move scraperblade 40 to'engage the wall. Thisengagement occurs before blade 31 is fully lowered.

When the skimming blade is fully lowered, cable 51 is slackened so thatsome movement of'member 44 and blade 40 FIG. 3 is a'plan view of theother end of the'skimming blade in the elevated position.

DESCRIPTION OF THEPREFERREDZEMBODIMENT The bridge includes the frame 11havingwheels at each end which roll on parallel rails fixed to andextend along the top of each side of the rectangularitank: Theflangedwheels l2 and 13 supporting one end of the bridge and the onerail 15 fixed to the top of the wall 16 forming one side of the tank areshown in FIG. 1. Wheel 12 and the correspondingotherwheel at the otherend of the bridge are driven by the 'moto'r 17 through the reductiongear unit 18andchain drive -19'which tumsshaft 20 on which thewheels aremounted. In the forward direction of travel which is to the left asshown, the sludge :scrap'er 21 is in the lower'position shown .in brokenlines to move the settled material over the floor 22:0f the tank towarda coilectinghopper, not shown. Scraper=21 is 'pivotally carried at thelower end of thew'frame 23 extending downwardly from bridge 10 and isconnected by rod 241to the control lever 25which also operatestheskimmerblade 31.

Blade 31 extends between the sidewalls 32 and 16 -1of the tank,respectively shown in FIGS; 2 and 3-and is carriedaby the arms 33 towhich the blade'isattached.

Arms 33 are fixed to shaft 34 whichis pivotally supported by spacedbearings including the bearing 35 carried by... brace 36. The lever 37extending'from shaft 34 .is adjustablyconnected by link 38 with lever 25so that when the sludge-scraper 21 is in the lower position, theskimming blade 31 is-supported above the water level of the tank.

As bridge 10 reaches one end of the tank, its travel reverses and thebridge then moves in the return, or' skimming direction. During suchreversah power-operated 'means; not

is allowed.

:zThis movement, within limits, allows the scraper 44 to be :heldagainstthe adjacent wall as thebridge 10 moves toward the otherend of the tank.As has been noted, the walls 16 and 32 of the tank may be onlyapproximately straight and the engagement of the two blades therewith isefiective over the entire length of the tank to keep the floatingmaterial or oil to be removed'from passing around the ends of blade 31.

As the bridge approaches the other end of the tank, the

floating material is pushed into a'trough not shown, from which it isdischarged. The trough may be of any'suitable arrangement. The mostcommon includes a'beach or ramp extending from'below the waterlevel tothe edge of the trough v which isabove the water level.

' When the floating material has been pushed into such a ntrough, thebridge 10 stops and the sludge scraper 21 is 5.5: relowered and theskimming blade 31 is again elevated.

tive length of cable 51 and pulls lever 49 to retract the scraper -blade40. The operation of the scraper blades 40 at both ends l The upwardmovement of the blade again reduces the effecof theskimming blade are orcan be adjusted to be simultaneous by adjusting the lengths of the twocables.

We claim:

l. ln combination with a reciprocating carriage carrying a skimmingblade in a lower position first to push material floating between thetwo parallel walls of a gravity separation tank shown, lifts sludgescraper 21 to its upperposition and'lowers the skimming blade31by1rotating shaft According to the present invention, each 1 end ofthe skimming blade is provided with an assembly including an extensiblescraper blade 40 which' forms an extension of the tank as the skimmingblade moves in its lower position, and a linkage connecting the scraperblade .and the carriage to retract the blades as the skimming blade iselevated to provide a clearance between the scraper blades and the wallsof the tank in the elevated, return position, said linkage beingoperable torelease the scraper blades as the skimming blade is reloweredforskimming.

2. In combination with a skimming blade carried by the reciprocatingbridge of a rectangular gravity separation tank, said bridge carryingsaid skimming blade in a lower position as the bridge travels in onedirection and in an upper position above the water level of the tankduring the return travel of the bridge; an extensible scraper bladecarried by and at each end of the skimming blade and which extend towardthe walls of the tank, springs having ends operatively connected to theskimming blade and to said two scraper blades and biasing the latter toengage and follow the walls of the tank, and linkage means connectingsaid scraper blades and the bridge at locations such that as theskimming blade is raised and approaches its upper position the linkageoperating against the springs retracts the scraper blades from the wallsof the tank and as the skimming blade is lowered the effective length ofthe linkage increases and first allows the springs to extend the scraperblades to engage the walls of the tank and thereafter to follow thewalls of the tank within limits.

3. In combination with the skimming blade of the reciprocating bridge ofa rectangular gravity separation tank, said skimming blade havingrearwardly extending support arms pivotally connected at their rear endsto the understructure of the carriage and being elevatable to an upperposition above the water level of the tank during the return run of thebridge; an extensible scraper assembly at each end of the skimming bladehaving a vertical scraper which extends toward the wall of the tank,each said assembly including a bracket attached to the end of theskimming blade, a scraper arm carried by said bracket for pivotalmovement about a vertical axis ahead of the end of the skimming blade, asection of said arm having a cylindrical surface concentric with itspivotal axis and adjoining the end of the skimming blade to formtherewith an operative seal, a vertical blade carried by said arm andextending toward the wall of the tank, a control lever connected to thearm, a spring having ends connected to said lever and blade assembly androtationally biasing said arm in one direction, and a cable connectingsaid lever and the understruc ture of the carriage at a location suchthat the cable is slack when the skimming blade is in its lower positionand is tightened when the skimming blade is in its upper position, thearrangement being such that as the skimming blade is pivotally raised toits upper position the cable operating against the spring turns the amand retracts the blade from the wall of the tank and as the skimmingblade is lowered the effective length of the cable increases and firstallows the spring to pivot the arm and move the scraper blade to engagethe wall of the tank and thereafter allows the blade to follow the wallof the tank within the limits of the operative seal.

4. A skimming blade and a reciprocating supporting structure therefor toeffect pushing of the floating material in a gravity separation tank toone end for removal therefrom and elevating the blade above the liquidlevel for return to the other end of the tank,.a laterally extensiblescraper blade at each end of the skimming blade and means connectedthereto and to the supporting structure such that the elevation of theblade effects lateral withdrawal of the scraper blades and relowering ofthe skimming blade laterally reextends the scraper blades to engage thesidewalls of the tank, said means including springs which bias thescraping blades laterally to maintain such engagement while pushing thematerial.

t i i

1. In combination with a reciprocating carriage carrying a skimmingblade in a lower position first to push material floating between thetwo parallel walls of a gravity separation tank and thereafter in anupper position for return movement of the skimming blade with thecarriage, extensible scraper blades carried at the ends of the skimmingblade, means biasing said scraper blades so that they follow and scrapethe walls of the tank as the skimming blade moves in its lower position,and a linkage connecting the scraper blade and the carriage to retractthe blades as the skimming blade is elevated to provide a clearancebetween the scraper blades and the walls of the tank in the elevated,return position, said linkage being operable to release the scraperblades as the skimming blade is relowered for skimming.
 2. Incombination with a skimming blade carried by the reciprocating bridge ofa rectangular gravity separation tank, said bridge carrying saidskimming blade in a lower position as the bridge travels in onedirection and in an upper position above the water level of the tankduring the return travel of the bridge; an extensible scraper bladecarried by and at each end of the skimming blade and which extend towardthe walls of the tank, springs having ends operatively connected to theskimming blade and to said two scraper blades and biasing the latter toengage and follow the walls of the tank, and linkage means connectingsaid scraper blades and the bridge at locations such that as theskimming blade is raised and approaches its upper position the linkageoperating against the springs retracts the scraper blades from the wallsof the tank and as the skimming blade is lowered the effective length ofthe linkage increases and first allows the springs to extend the scraperblades to engage the walls of the tank and thereafter to follow thewalls of the tank within limits.
 3. In combination with the skimmingblade of the reciprocating bridge of a rectangular gravity separationtank, said skimming blade having rearwardly extending support armspivotally connected at their rear ends to the understructure of thecarriage and being elevatable to an upper position above the water levelof the tank during the return run of the bridge; an extensible scraperassembly at each end of the skimming blade having a vertical scraperwhich extends toward the wall of the tank, each said assembly includinga bracket attached to the end of the skimming blade, a scraper armcarried by said bracket for pivotal movement about a vertical axis aheadof the end of the skimming blade, a section of said arm having acylindrical surface concentric with its pivotal axis and adjoining theend of the skimming blade to form therewith an operative seal, avertical blade carried by said arm and extending toward the wall of thetank, a control lever connected to the arm, a spring having endsconnected to said lever and blade assembly and rotationally biasing saidarm in one direction, and a cable connecting said lever and theunderstructure of the carriage at a location such that the cable isslack when the skimming blade is in its lower position and is tightenedwhen the skimming blade is in its upper position, the arrangement beingsuch that as the skimming blade is pivotally raised to its upperposition the cable operating against the spring turns the arm andretracts the blade from the wall of the tank and as the skimming bladeis lowered the effective length of the cable increases and first allowsthe spring to pivot the arm and move the scraper blade to engage thewall of the tank and thereafter allows the blade to follow the wall ofthe tank within the limits of the operative seal.
 4. A skimming bladeand a reciprocating supporting structure therefor to effect pushing ofthe floating material in a gravity separation tank to one end forremoval therefrom and elevating the blade above the liquid level forreturn to the other end of the tank, a laterally extensible scraperblade at each enD of the skimming blade and means connected thereto andto the supporting structure such that the elevation of the blade effectslateral withdrawal of the scraper blades and relowering of the skimmingblade laterally reextends the scraper blades to engage the sidewalls ofthe tank, said means including springs which bias the scraping bladeslaterally to maintain such engagement while pushing the material.